JP2016537507A - Method for monitoring Se vapor in a vacuum reactor apparatus - Google Patents

Abstract

A method and system for monitoring vapor in a vacuum reactor apparatus is disclosed. The system includes: (a) a vacuum chamber; (b) a steam source stored in the vacuum chamber, the steam source configured to generate steam; and (c) stored in the vacuum chamber; A reaction vessel connected to a vapor source having an outlet to a vacuum chamber for receiving vapor from the vapor source and discharging a portion of the received vapor into the vacuum chamber through the outlet (D) one or more sensors stored in a vacuum chamber, the one or more sensors configured to detect vapor released through the outlet; Have [Selection] Figure 1

Description

This application claims priority to US Provisional Application No. 61 / 905,175, filed Nov. 16, 2013, which is hereby incorporated by reference in its entirety.

  Unless otherwise specified herein, the materials described in this section are not prior art to the claims of this application and are not admitted to be prior art by inclusion in this section.

  A system for monitoring the vapor pressure in the reactor chamber is utilized in applying vapor (eg, selenium) to a substrate, for example, to make a thin film solar cell. A typical reactor chamber includes a vacuum chamber, a vapor source, and a reaction vessel. Some conventional systems monitor steam at the steam source to control the temperature of the steam source. The combination of the thermal mass of the vapor source and the nature of the selenium that reacts can, for example, change the temperature very slowly in response to control feedback. In addition, fluctuations due to actual reaction perturbations in the reaction vessel due to reaction sample differences or leakage between the reaction vessel and the vacuum chamber are not accounted for. Furthermore, current systems are expensive, prone to failure and cannot operate over the required duration or at the high operating temperatures that exist in the manufacturing environment.

  Exemplary embodiments provide a steam monitoring system and method configured to direct a flow of steam from a high pressure zone in a reaction vessel to a lower pressure zone in a vacuum chamber and to detect the steam with a sensor. . This arrangement advantageously provides feedback that is correlated with the amount of steam in the reaction vessel. The system further beneficially provides a valve to maintain a certain amount of steam in the reaction vessel with immediate control of the rate of vapor transfer from the vapor source to the reaction vessel. In addition, in embodiments that use an ion gauge or selenium velocity monitor, the sensor has the advantage of being less sensitive to temperature than other sensors, and is free from the presence of ions rather than being coated with vapor material. Detect and weigh, resulting in fewer replacement parts and increased sensor life.

  Thus, in one aspect, (a) a vacuum chamber; (b) a steam source stored in the vacuum chamber, the steam source configured to generate steam; and (c) in the vacuum chamber A reaction vessel stored and connected to a vapor source, having an outlet to a vacuum chamber, for receiving vapor from the vapor source, and passing a portion of the received vapor into the vacuum chamber through the outlet A reaction vessel configured to release; and (d) one or more sensors stored in a vacuum chamber, the one or more sensors configured to detect vapor released through the outlet. A system is provided.

  In another aspect, (a) moving the steam from the high pressure region to the intermediate pressure region through the valve; and (b) releasing a part of the moved steam from the intermediate pressure region to the low pressure region through the outlet. (C) detecting vapor released through the outlet by a sensor in the low pressure region.

  These and other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings.

1 is a schematic diagram of a system for monitoring steam in a vacuum reactor apparatus, according to an example embodiment. FIG. 1 is a front view of an exemplary embodiment of a system for monitoring steam using a microbalance sensor. FIG. 2B is a side cross-sectional view of a system for monitoring the steam of FIG. 2A. FIG. Example system for monitoring steam utilizing an ion gauge sensor or selenium rate monitor sensor ("SRM") and two additional microbalance sensors that are offset from the exit and path of the emitted steam flow It is a front view of embodiment which becomes. 3B is a side cross-sectional view of the system for monitoring the steam of FIG. 3A. FIG. 1 is a front view of an exemplary embodiment of a system for monitoring vapor utilizing two ion gauges or SRM sensors. FIG. FIG. 4B is a top cross-sectional view of the system for monitoring the steam of FIG. 4A. 4D is a side cross-sectional view of a system for monitoring the steam of FIG. 4C. FIG. 6 is a graph illustrating the response of a microbalance sensor relative to the rate of selenium vapor transfer from a vapor source to a reaction vessel, according to an example embodiment. 6 is a graph illustrating the response of an ion gauge relative to the rate of selenium vapor transfer from a vapor source to a reaction vessel, according to an example embodiment. 2 is a method according to an exemplary embodiment.

  Examples of methods and systems are described herein. Any exemplary embodiment or feature described herein is not necessarily to be construed as preferred or advantageous over other embodiments or features. The example embodiments described herein are not intended to be limiting. It will be readily appreciated that certain aspects of the disclosed systems and methods can be arranged and combined in a variety of different configurations, all of which are contemplated herein.

  Furthermore, the specific arrangements shown in the figures should not be considered as limiting. It should be understood that other embodiments may include more or less of each element shown in the attached figures. In addition, some of the illustrated elements may be combined or omitted. Still further, example embodiments may include elements not illustrated in the figures.

  This embodiment advantageously provides a system for monitoring and controlling the steam released from the high pressure region to the low pressure region. With reference now to FIGS. 1-2B, a system having a vacuum chamber 5 is shown. The vapor source 10 is stored in the vacuum chamber 5. The steam source 10 is configured to generate steam. In some embodiments, the steam source 10 comprises a crucible and the steam is generated by one or more heating elements that increase the temperature of the steam source 10 and cause evaporation of the vacuum-compatible material. The operating temperature of the steam source 10 is maintained in the range of about 250 ° C to about 450 ° C, preferably in the range of 300 ° C to about 370 ° C. In various embodiments, organic and inorganic vacuum compatible materials can be used, for example, as vapor for deposition applications. In a preferred embodiment, the vapor includes selenium. In various other embodiments, the vapor may comprise, for example, sulfur, or other evaporable selenium or sulfur containing compounds.

  Similarly, the reaction vessel 15 is stored in the vacuum chamber 5 and connected to the vapor source 10 via a conduit 11. The reaction vessel 15 defines a chamber in which a substrate can be stored, for example for roll-to-roll processing. In various embodiments, the conduit 11 includes a tube or any other passage. Reaction vessel 15 and conduit 11 each comprise any material capable of withstanding the operating temperatures and selenium vapor described above, such as stainless steel. In some embodiments, reaction vessel 15 and conduit 11 can be independently heated to maintain a desired operating temperature.

  The reaction vessel 15 has an outlet 16 to the vacuum chamber 5. The reaction vessel 15 is further configured to receive vapor from the vapor source 10 and to discharge a portion 17 of the received vapor into the vacuum chamber 5 through the outlet 16. In some embodiments, the outlet 16 comprises an opening that communicates directly with the chamber of the reaction vessel 15. In an alternative embodiment, the reaction vessel 15 may further comprise a tunnel 18 that connects the chamber of the reaction vessel 15 to the outlet 16, as shown in FIGS. 2B, 3B, and 4B, where the tunnel 18 is , Having a diameter larger than the diameter of the outlet 16. In these embodiments, the reaction vessel 15 maintains a high temperature within the chamber of the reaction vessel 15. The reaction vessel 15 further includes a housing 13 that defines a region 14 having a temperature that is controlled independently of the temperature of the chamber, for example, by a thermocouple 12. In these embodiments, the tunnel 18 and outlet 16 are defined in the region 14 of the reaction vessel housing 13, both of which are at least partially contained within the radiation shield 24. The tunnel 18 provides an intermediate path for directing vapor from the chamber of the reaction vessel 15 to the outlet 16. In some embodiments, the outlet 16 may itself comprise an elongate conduit 19 on the opposite side of the basic opening.

In one embodiment, the vapor source 10 has a first pressure P1, the reaction vessel 15 has a second pressure P2, and the vacuum chamber 5 has a third pressure P3. In various embodiments, the first pressure P1 is greater than the second pressure P2, and the second pressure P2 is greater than the third pressure P3. The first pressure may range from about 10 ⁺¹ to about 10 ^-2 , the second pressure may range from about 10 ^-2 to about 10 ^-4 , and the third pressure is About 10 ⁻⁴ to about 10 ⁻⁶ . Due to the nature of the steam, the steam flows from the high pressure region P 1 in the steam source 10 to the medium pressure region P 2 in the reaction vessel 15 and the low pressure region P 3 in the vacuum chamber 5. Each pressure is a factor of the temperature of the vapor source 10, the reaction vessel 15, and the vacuum chamber 5, and the vacuum pressure applied directly to the vacuum chamber 5 to maintain the desired pressure P3.

  One or more sensors 20 are stored in the vacuum chamber 5. One or more sensors 20 are configured to detect vapor 17 released through outlet 16. In a preferred embodiment, the vapor 17 is released in a flow and the sensor 20 is positioned directly in or near the flow path. In another preferred embodiment, the outlet 16 is positioned on the top surface of the reaction vessel 15, but the outlet may be positioned on the side of the reaction vessel 15 to achieve the same result.

In various embodiments, the sensor may be a microbalance (FIGS. 2A-B and 3A-3B), an ion gauge or aka selenium rate monitor (SRM) (FIGS. 3A-B, 4A-C), or a combination of the two (see FIG. 3A-B, 4A-C). A microbalance is an instrument configured to measure the weight of condensed particles having a very small mass, ie, about 1 part per million grams. Microbalance may include quartz crystal microbalance (“QCM”), which is a sensitive mass deposition sensor that depends on the piezoelectric properties of the quartz crystal. Since the resonant frequency is highly dependent on the change in crystal mass, the QCM uses the resonant frequency of the crystal to measure the mass on the surface of the sensor. QCM can measure mass deposition as small as 0.1 nanogram. FIG. 5 shows that the steam flow rate increases as the valve 25 (described below) opens, and the steam density recorded by the QCM increases as well. The QCM is for measuring the amount or weight of the material condensed on the quartz crystal surface. The sensor operates on the assumption that the material is uniformly deposited and converts the amount or weight to the equivalent thickness of the thin film, where A / second represents angstroms or a thickness of 10 ⁻¹⁰ m.

The ion gauge and selenium rate monitor (“SRM”) are each configured to be used in a low pressure (vacuum) environment. Ion gauges and SRMs sense pressure indirectly by measuring the electrical ions that are generated when the vapor undergoes electron bombardment, where lower density vapors produce fewer ions. There are two main types of ion gauges: hot cathodes and cold cathodes. In operation, the hot cathode gauge includes an electrically heated filament that is used to generate an electron beam. The electrons travel through the gauge and ionize surrounding vapor molecules. These resulting ions are then collected at the negative electrode. The current generated corresponds to the number of ions, which in turn corresponds to the vapor pressure recorded by the gauge. The hot cathode gauge is accurate from about 10 ⁻³ Torr to about 10 ⁻¹⁰ Torr. Cold cathode gauges operate in a similar manner, the difference being that electrons are generated via a high pressure discharge. The cold cathode gauge is accurate from about 10 ⁻² Torr to about 10 ⁻⁹ Torr. FIG. 6 shows that as the valve 25 opens, the steam flow rate increases and the steam density recorded by the SRM increases as well, arbitrary units divided by 10 ⁻⁴ torr. Represents pressure.

  In one embodiment shown in FIGS. 2A-B, the one or more sensors 20 include a single microbalance positioned directly on the outlet 16. In this arrangement, the outlet 16 is configured as a conduit 19 or tube having an inner diameter that can range from about 0.1 cm to about 0.5 cm, and can extend from the reaction vessel 15 from about 2 cm to about 5 cm. The microbalance can be positioned about 0.5 cm to about 1.5 cm away from the outlet 16 to obtain accurate measurements. In one embodiment, the cooling water line 25 may be coupled to the microbalance 20.

  In another embodiment shown in FIGS. 3A-B and 4A-C, the one or more sensors comprise a first sensor and a second sensor each stored in a vacuum chamber 5. In one exemplary embodiment shown in FIGS. 4A-C, the first sensor 21 and the second sensor 22 are each offset from the outlet 16 and from the direct path of the emitted vapor stream 17. The opening of the outlet 16 is configured in the form of a nozzle that is substantially recessed in the reaction vessel. The outlet nozzle 16 disperses the flow into the cylinder 30, which defines a channel 31 that communicates with the first and second sensors 21, 22, for example. Channel 31 is configured to contain the majority of the vapor emitted from outlet 16. Channel 31 defines different pressure zones that are read by one or more ion gauges. In some embodiments, the vacuum nipple is of sufficient diameter to accommodate an ion gauge. In this arrangement, the first and second sensors 21, 22 are ion gauges or selenium velocity monitors arranged on the opposite side of the channel 31. The second sensor 22 may be used, for example, to confirm the result of the first sensor 21.

  In another exemplary embodiment shown in FIGS. 3A-B, a third sensor 23 is provided so that the first sensor 21 is positioned directly on the outlet 16 while the second sensor 22. And the third sensor 23 is displaced from the outlet 16. In this arrangement, the first sensor 21 is an ion gauge or selenium velocity monitor, and the second and third sensors 22, 23 are microbalance. Similar to the embodiment shown in FIGS. 4A-C, the opening of the outlet 16 is again configured in the form of a nozzle that disperses the flow of steam into the cylinder 30, which communicates with the first sensor 21, for example. A channel 31 is defined. The second and third sensors 22, 23 are arranged on the opposite side of the cylinder 30, and the vapor is defined on one side of the cylinder 30 and is on the microbalance via an outlet (not shown) communicating with the channel 31. Oriented to. These second and third sensors 22, 23 may be used, for example, to confirm the result of the first sensor 21.

  In one embodiment, the system 1 includes a valve 25 configured to control the amount of steam from the steam source 10 received by the reaction vessel 15. In various embodiments, the valve 25 is disposed between the vapor source 10 and the reaction vessel 15, preferably at a location along the conduit 11. Alternatively, the valve may be located at the vapor outlet above the vapor source 10 or at the vapor inlet above the reaction vessel 15. The valve 25 controls the amount of steam, either partially or fully, depending on the situation, through opening and / or closing operations. In a further embodiment, valve 25 is configured to control the amount of steam in response to one or more control signals 26. These control signals 26 may be generated by a controller that communicates with one or more sensors 20 and valves 25. The controller may include a processor and memory for analyzing control signals or feedback 26 from one or more sensors 20 and determining, if present, adjustments to be made in the valve 25. In various embodiments, the controller can process feedback or control signals 26 from the plurality of sensors 21, 22, and / or 23 to determine if the sensors need to be calibrated or replaced. In some embodiments, the system operator may be able to provide manual override instructions to the controller via a control panel, keyboard, or other input device.

  FIG. 7 is a flowchart of a provided method 700 that includes the step 705 of moving steam through the valve 25 from the high pressure zone P1 to the intermediate pressure zone P2. The method 700 further includes a step 710 of discharging a portion 17 of the transferred vapor from the intermediate pressure zone P2 through the outlet 16 to the low pressure zone P3 in the vacuum chamber 5. The method 700 also includes a step 715 of detecting the vapor 17 emitted through the outlet 16 by the sensors 20, 21 in the low pressure zone P1. In various other embodiments, the method detects the vapor released through the outlet 16 by the second sensor 22 in the low pressure zone P3 and the outlet by the third sensor 23 in the low pressure zone P3. And detecting the vapor released through 16.

  In some embodiments, the method 700 further includes generating a control signal based on the steam 17 detected by the sensor 20 and controlling the valve 25 based on the control signal 26. In various embodiments, controlling the valve 25 based on the control signal 26 includes controlling the speed of steam movement from the high pressure zone P1 to the intermediate pressure zone P2. In still other embodiments, the method 700 also generates steam in the high pressure zone P1, generally located in the steam source 10, and generates steam in the intermediate pressure zone P2, generally located in the reaction vessel 15. Reacting. The method may be implemented using any of the system embodiments described above.

The above detailed description describes various features and functions of the disclosed systems and methods with reference to the accompanying drawings. While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being defined by the following claims. Indicated.

  In one embodiment shown in FIGS. 2A-B, the one or more sensors 20 include a single microbalance positioned directly on the outlet 16. In this arrangement, the outlet 16 is configured as a conduit 19 or tube having an inner diameter that can range from about 0.1 cm to about 0.5 cm, and can extend from the reaction vessel 15 from about 2 cm to about 5 cm. The microbalance can be positioned about 0.5 cm to about 1.5 cm away from the outlet 16 to obtain accurate measurements. In one embodiment, the cooling water line 35 may be coupled to the microbalance 20.

Claims (20)

A vacuum chamber;
A steam source stored in the vacuum chamber, the steam source configured to generate steam;
A reaction vessel housed in the vacuum chamber and connected to the vapor source, having an outlet to the vacuum chamber, for receiving the vapor from the vapor source, and the received vapor A reaction vessel configured to discharge a portion of the gas through the outlet into the vacuum chamber;
One or more sensors stored in the vacuum chamber, the system comprising: one or more sensors configured to detect the vapor emitted through the outlet.   The system of claim 1, further comprising a valve configured to control the amount of the steam from the steam source received by the reaction vessel.   The system of claim 2, wherein the valve is configured to control the amount of the steam in response to one or more control signals.   The said system as described in any one of Claims 1-3 in which the said vapor | steam contains selenium.   5. The system according to any one of claims 1-4, wherein the sensor comprises a microbalance, ion gauge, or selenium rate monitor.   6. The vapor source according to claim 1, wherein the vapor source has a first pressure, the reaction vessel has a second pressure, and the vacuum chamber has a third pressure. Of the system.   The system of claim 6, wherein the first pressure is greater than the second pressure, and the second pressure is greater than the third pressure. The first pressure ranges from about 10 ^{+ 1} to about ^10-2 , the second pressure ranges from about ^10-2 to about ^10-4 , and the third pressure ranges from about ^10-2. 8. The system of claim 6 or 7, wherein the system ranges from ^-4 to about ^10-6 .   9. The system of any one of claims 1 to 8, wherein the one or more sensors comprise a first sensor and a second sensor each stored in the vacuum chamber.   The system of claim 9, wherein the first sensor is positioned directly on the outlet and the second sensor is offset from the outlet.   The system of claim 9 or 10, further comprising a third sensor, wherein the third sensor is offset from the outlet.   The system of claim 9, wherein the first sensor and the second sensor are each offset from the outlet. Moving steam from high pressure to medium pressure through a valve;
Discharging a portion of the transferred steam from the intermediate pressure region to the low pressure region through an outlet;
Detecting the vapor released through the outlet by a sensor in the low pressure region. Generating a control signal based on the steam detected by the sensor;
The method of claim 13, further comprising controlling the valve based on the control signal.   14. The method of claim 13, wherein controlling the valve based on the control signal includes controlling a rate of movement of the steam from the high pressure region to the intermediate pressure region.   16. The method according to any one of claims 13 to 15, wherein the vapor comprises selenium.   16. The method of any one of claims 13-15, wherein the sensor comprises a microbalance, ion gauge, or selenium rate monitor. Generating the steam in the high pressure region;
The method according to any one of claims 13 to 17, further comprising reacting the steam in the intermediate pressure region. Detecting the vapor released through the outlet by a second sensor in the low pressure region;
18. The method according to any one of claims 13 to 17, further comprising detecting the vapor released through the outlet by a third sensor in the low pressure region.   20. The method according to any one of claims 13-19, wherein the method is performed using the system according to any one of claims 1-12.

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